Electrically and thermally conductive shield



March 28, 1967 D. A. MELNICK 3,311,696

ELECTRICALLY AND THERMALLY CONDUCTIVE SHIELD Filed June 18, 1965 2Sheets-Sheet l INVENTOR. DOA/4A0 4. M54 A/lCAf,

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28, 1967 D. A. MELNICK ELECTRICALLY AND THERMALLY CONDUCTIVE SHIELDFiled June 18, 1965 2 Sheets-Sheet 2 AV Av INVENTOR.

United States Patent 3,311,696 ELECTRICALLY AND THERMALLY CONDUCTIVESHIELD Donald A. Melnick, 7301 Birch Ave., Takoma Park, Md. 20012 FiledJune 18, 1965, Ser. No. 465,043 11 Claims. (Cl. 174-18) This inventionrelates to electrically or thermally conductive web or sheet material,and more particularly to conductive tape or sheet material for use incovering immersion heating electrodes, freezer units, or similarelements employedfor conduction of electrical current or heat to or.froma contiguous adjacent medium, wherein it is desirable vto protectthe electrodes or corresponding unit from undesired deposits from saidmedium.

A main ,object of the invention is to provide a novel andimprovedexpendablecovering material for electrodes, freezer units, or the like,the covering material being of simple construction, providing highlyefficient conduction, and being easy to install and remove.

A further object .of the invention is to provide, an improved web orsheet material for use in covering electrodes, freezer units, or similarelements wherein electrical current or heat is to be conducted to orcollected from a surrounding medium, the web or sheet covering materialserving as a means for collecting sediment, frost, or other undesireddeposits from the surrounding medium, the material being inexpensive tofabricate, being rugged in construction, being sufficiently pliable toaccurately conform with the surfaces to which it is to be applied, andbeing easy to strip off for unloading or replacement.

A still further object. of the invention is to provide an improvedexpendable tape or sheet material for use as a protective conductingcover for electrodes, freezer units, and similar elements exposed in amedium, primarily fluid mediums, either liquid or gaseous, wherein thereis a tendency for material to be deposited on the elements .beingprotected, the covering material serving to receive such deposits and toeliminate the necessity of cleaning the elements, the material beingrelatively thin and pliable as well as being highly conductive,andbeingconstructed so that it does not in any way interfere with thenormal operation of the elements covered thereby.

Further objects and advantages of the invention will become apparentfrom the following description and claims, and from the accompanyingdrawings, wherein:

FIGURE 1 is a perspective view of a length of adhesive tape materialconstructed in accordance with the present invention and shown with aportionof the outer metal foil layer thereof separated from theremainder thereof to clarify structural details.

FIGURE 2 is an enlarged transverse vertical cross sectional view takensubstantially on the line 2-2 of FIGURE 1.

FIGURE 3 is a perspective view, partly in cross'section, taken throughan electrical vaporizer assembly whose electrodes are covered withconductive tape material such as that shown in FIGURES 1 and 2.

FIGURE 4 is an enlarged elevationalview of the electrodes of thevaporizer of FIGURE 3, one of the protective tape elements being shownpartly detached from its associated electrode so as to illustrate themanner in which the tape elements are applied to the electrodes.

FIGURE 5 is an enlarged horizontal cross sectional view takensubstantially on the line. 55 of FIGURE 4.

FIGURE 6 is a perspective view of a piece of wide covering material inthe form of a relatively wide web for use in covering refrigeratorfreezer units, or similar large freezing or other thermal-activesurfaces, a corner portion of the mateial being opened up to reveal theinternal construction of the material.

FIGURE 7 is a perspective view of a typical refrigerator freezer unitand illustrating the manner in'which a sheet of the material shown inFIGURE 6 is applied thereto'for the purpose of acting as a frostcollector.

FIGURE 8 is a perspective view showing a fragmentary portion of analternative form of conductive sheet material which may be employed inthe same manner as the material shown in FIGURE 6.

FIGURE 9 is a perspective view showing still another alternative form ofconductive material which may be em ployed in the same manner as thematerial shown in FIG- URES 6 and 8.

Referring to the drawings, and more particularly to FIGURES 1 to 5, 11generally designates a typical form of expendable pliable tapematerialwhich may be employed in accordance with the present invention to coverelectrode elements for the purpose of protecting said electrode elementsagainst direct accumulation thereon of sediment or scale material, sincesuch deposits ordinarily require considerable effort and time inscraping off and removing the deposits. The protective tape material 11therefore is employed to cover such electrodes and to collect theundesirable deposits, the tape material being easy to apply to theelectrodes and being similarly easy to strip off the electrodes after aconsiderable amount of scale or other deposits have accumulated thereon.After removal, the tape material may be merely discarded or, if sodesired, may be suitably laundered or cleansed and reused.

The tape material 11 comprises an outside layer 12, which may consist ofpliable metal foil, such as aluminum foil, or the like. Secured in anysuitable manner to the bottom surface of the outer conductive metalliclayer 12 is a relatively wide mesh metallic screen or grid 13 of finewire material coextensive in width with the outer metal foil strip 12and conductively integral therewith. The spaces in the wire meshmaterial 13 are filled with adhesive material 14'of any conventionalcomposition, for example, of the same composition as is employed inordi-- nary pressure-sensitive adhesive tape, the material beingpreferably of a type having stability over a wide temperature range,including the boiling point temperature of water or of other liquidswhich may be employed in the devices with which the tape is intended tobe used. There are many commercial adhesive materials which are suitablefor this purpose and which are capable of adhering to both the metallicportions of the tape 11 and to themetal electrode surfaces with whichthe tape is employed at the operating temperatures of the electrodes.The thickness of the layer of adhesive material 14 is sub-' stantiallyidentical with the thickness of the wire mesh screen 13 so that when thetape is installed on a stationary electrode the wire mesh screen 13makes electrical contact with the electrode as well as beingelectrically connected with the outer metallic foil strip 12, wherebysaid outer metallic strip 12 becomes electrically connected to theelectrode so that there is no electric field between the tape and theelectrodeand hence there is no heating, bubbling or deposit of sedimentin this region.

In using the covering tape 11, suitable lengths thereof are cut off andare respectively installed on the electrodes to be protected, forexample, the pair of electrodes 15 and 16 of a conventional watervaporizer 17 shown in FIGURE 3. The strips of tape 11 are of sufficientlength to cover the major portions of-the surfaces of the electrodes 15and 16 and to extend a short distance below the electrodes. The stripsof tape 11 are placed lengthwise on the electrodes and tightly wrappedaround same in the manner illustrated in FIGURE 4, forming a lengthwiseoverlapping seam at their meeting vertical margins, with the bottomportion of the strip bent horizontally and outwardly, as shown at 19 inFIGURES 4 and 5. The outwardly projecting tab elements 19 provide ameans for grasping and manipulating the lower portion of the tape whenit is to be unwrapped and stripped off the electrodes after aconsiderable period of use during which substantial deposits of sedimenthave collected on the exposed outer metallic foil elements 12.

As will be readily apparent from FIGURE 2, the grid wires 13 are locatedso as to make good electrical contact with the surfaces of theelectrodes 15 and 16, so that the covering strips of tape 11 act aselectrical extensions of the electrodes and provide efficient conductionof electric current to the liquid in which the electrodes are immersed.

To remove the covering strips of conductive tape 11, the tabs 19 aremerely bent downwardly to vertical positions, providing access to thebottom corners of the overlapping margins ofthe strips, whereby saidmargins may be disengaged from each other and whereby the stfip may beeasily detached from the electrodes.

The wire elements of the wire mesh layers 13 are preferably flattened attheir points of transverse crossing, as shown at 40, so as to maintainthe thickness of the wire mesh layers 13 substantially uniformthroughout.

Although the electrodes 15 and 16, illustrated in FIG- URES 4 and 5 aregenerally cylindrical in shape, the conductive tape material 11 may bealso employed with equal efficiency with electrodes of other crosssectional shape.

As will be presently described, the screen material 13 may be formedintegrally with the outer covering layer 12, and does not necessarilyhave to be in the form of a two-dimensional grid. It may be in the formof a onedimensional array of linear elements which protrude through theadhesive layer 14, or it may simply be an array of spaced dot elementswhich similarly protrude through the adhesive.

Referring now to FIGURES 6 and 7, 11' designates a web of materialsimilar in construction to the relatively narrow tape material 11 shownin FIGURE 1, and comprising an outer layer of pliable metal foil 12', agrid of pliable thin wide-mesh pliable wire material 13', and a layer ofadhesive material 14 similar to that employed in the embodiment ofFIGURE 1 and filling the spaces of the wire mesh material 13 whileallowing the wire mesh to be exposed at the bottom of the sheet 11'. Thematerial 11' may be employed as a protective cover to facilitatedefrosting of the freezer units of refrigerators, deep freeze equipment,or the like. Thus, the web material 11 is preferably of at leastsufficient width to span the depth of a conventional refrigeratorfreezer unit 20, shown in FIGURE 7. A suitable length of the webmaterial 11' is cut 011?, preferably sufficient to completely cover thethermally conductive wall surface 21 of the freezer unit 20 whichcontains the evaporation coil channels 22. Where possible, the webmaterial 11 is also applied to the inside wall surface 21a and shelf 25.As shown in FIGURE 7, the web material is applied so as to projectbeyond the end 28 of the freezer unit 20 to prevent the accumulation offrost around the edge of the open end and to facilitate the removal ofthe web material with the accumulated frost thereon.

The length of conductive web material 11 is applied to the wall surfaceof the freezer unit 20, and is sufiiciently pliable so that it closelyconforms to the contour of said wall surface and adheres thereto by theadhesive action of the material 14' incorporated in the cover element11'. The wire mesh elements 13' are in thermally conductive contact withthe surface of the freezer unit wall 21 substantially over the entirearea of the covering material, so that heat is conducted to the foilouter layer 12 from the interior of the associated refrigerator and thento the wall surface 21 and freezer unit coil channels 22 through theconductive wire mesh layer 13'. Therefore, the thermal eficiency of thefreezer unit 20 is in no way impaired, while at the same timeaccumulations of frost occur on the protective covering member 11'rather than directly on the wall surface 21 of the freezer unit. After asubstantial amount of frost has accumulated on the cover sheet, thesheet is merely stripped off the freezer unit, and may be replaced byanother protective sheet 11'. The previously used protective cover sheetmay be allowed to thaw out in a sink or bucket, whereby the cover sheetmay be reused, if so desired.

In order to decrease the amount of chopping of ice required to removethe sheet adjacent the edges thereof, the sheet is preferably somewhatgreater in width than the depth of the freezer unit 20, so that theedges of the protective cover sheet 11' protrude beyond the edges of thewall of the freezer unit. It is preferable to employ a somewhat denserconductive grid in the modification shown in FIGURES 6 and 7 than wasemployed in the form of the invention illustrated in FIGURES 1 to 5 soas to avoid presenting too high a thermal resistance through the grid13'. The metal of the grid 13 preferably should cover at least an areaof the order of ten percent of the area of the conductive outer metallicfoil layer 12 in order to prevent too high a thermal resistance throughthe grid. It is also preferable to employ an outer foil layer 12' ofsubstantial thickness, whereby "to assist, by lateral conduction, inbridging any areas of imperfect contact between the grid 13' and theadjacent surfaces of the freezer wall 21.

FIGURE 8 illustrates a modification of the webbing material 11' whereinthe pliable grid, designated at 23,

-is formed integrally with the pliable main foil element 12 of the coversheet, shown at 24. The spaces in the integral pliable grid 23 arefilled with the adhesive material 14 in the same manner as illustratedin FIGURE 6. As previously mentioned, instead of employing atwodimensional grid arrangement, a one-dimensional array of parallelribs or line elements may be used, formed intergally with the pliableconductive foil member 12 and exposed through the adhesive material 14'.As a further alternative, the conductive intervening screen employedwith the foil sheet 12 may comprise an array of dot-like projections 26,as shown in FIGURE 9, said projections being formed integrally with thefoil sheet 12' and exposed through the layer of adhesive material, shownat 27 in FIGURE 9.

While certain specific embodiments of an improved conducting coveringmember for use with electrical or thermal-active elements have beendisclosed in the fore going description, it will be understood thatvarious modifications within the spirit of the invention may occur tothose skilled in the art. Therefore, it is intended that no limitationsbe placed on the invention except as defined by the scope of theappended claims.

What is claimed is:

1. A pliable conductive shield comprising a body of thinmalleable sheetmetal, uniformly distributed substantially uni-planar conductiveprojection means secured to the bottom surface of said body inconductive contact therewith, and a layer of adhesive material on saidbottom surface and being substantially flush with. said projection meansfor securing the shield to a metal surface with said projection means inconductive engagement with the metal surface.

2. A pliable conductive shield comprising a body of thin malleable sheetmetal, a conductive grid secured to the bottom surface of said body inconductive contact therewith, and a layer of adhesive material on saidbottom surface with the bottom surface of said adhesive layersubstantially flush with the bottom plane of said grid for securing theshield to a metal surface with said grid in conductive engagement withthe metal surface.

3. A pliable conductive shield device comprising a web of malleablemetal foil, substantially uniformly distributed uni-planar malleablemetal spaced projection means conductivelv secured to the bottom surfaceof said web, and adhesive material on said bottom surface filling thespaces defined by said projection means but being substantially flushwith the bottom surface of the projection means for securing the devicein covering relation to a conductive metal surface with the projectionmeans held in conductive contact with said metal surface.

4. A pliable conductive shield comprising a web of malleable metal foil,a malleable wire mesh grid conductively secured to the bottom surface ofsaid web and extending substantially over the area defined by saidbottom surface, and adhesive material on said bottom surface in themeshes of said grid and being substantially flush with the bottom planeof the grid for securing the shield in covering relation to a metalsurface with the grid in conductive contact with said metal surface.

5. An electrode shield comprising a web of malleable metal foil, amalleable wire mesh grid conductively secured to the bottom surface ofsaid web and being distributed over the area of said bottom surface, andadhesive material in the meshes of said'grid and being substantiallyflush with the bottom plane of the grid for securing the shield aroundan electrode with the grid in conductive contact therewith.

6. In combination, a metal body exposed in a fluid medium, a conductivemetal foil member covering said body, a wire mesh intermediate membersecured conductively to the inner surface of said foil member andconductively engaging said body, and adhesive material carried in themeshes of said intermediate member and adhesively securing the foilmember to the body, whereby said foil member is a conductive extensionof said body in said medium.

7. In combination, an electrode, a web of malleable metal foil wrappedaround said electrode, and a malleable electrically conductive gridinterposed between the web and the electrode in conductive contact withsaid web and electrode, and means securing said foil to said electrode.

8. In combination, an electrode, a web of malleable metal foil wrappedaround said electrode, a malleable electrically conductive gridinterposed between the web and the electrode in conductive contact withsaid web and electrode and adhesive material in the meshes of said gridsecuring the web to the electrode.

9. In combination, an electrode, a web of malleable metal foil wrappedaround the electrode, a layer of malleable wire screen materialinterposed between the web and the electrode, said layer beingconductively secured to the web and being in conductive contact with theelectrode, and adhesive material disposed in the meshes of said wirescreen material and being in adhesive contact with the electrode,whereby to secure the web to the electrode with the web forming aconductive extension of the electrode.

M. In an enclosure containing a fluid medium, a metal body projectinginto the enclosure and being normally subjected to depositions ofmaterial from the medium, and detachable shield means on the body toreceive such depositions of material, said shield means comprising aconductive malleable metal foil member covering a substantial portion ofthe surface area of said body, malleable metal grid means interposedbetween the foil member and the surface area covered thereby and beingin conductive relationship between the foil member and said surfacearea, and adhesive material carried in the spaces defined by said gridmeans and adhesively securing the foil member to said surface area,whereby said foil member defines a conductive extension of said metalbody in said fluid medium.

11. In an enclosure containing a fluid medium, a metal body projectinginto the enclosure and being normally subjected to depositions ofmaterial from the medium, and detachable shield means on the body toreceive such depositions of material, said shield means comprising aconductive malleable metal foil member covering a substantial portion ofthe surface area of said body, malleable metal grid means interposedbetween the foil member and the surface area covered thereby and beingin conductive contact with said member and said surface area, andadhesive material carried in the spaces defined by said grid means andadhesively securing the foil memher to said surface area, whereby saidfoil member defines a conductive extension of said metal body in saidfluid medium, said foil member having a free portion ex- I tendingoutwardly from the metal body and serving as a tab means for strippingthe shield member from the body.

References Cited by the Examiner UNITED STATES PATENTS 2,808,352 10/1957Coleman et a1.

LARAMIE E. ASKIN, Primary Examiner.

1. A PLIABLE CONDUCTIVE SHIELD COMPRISING A BODY OF THIN MALLEABLE SHEETMETAL, UNIFORMLY DISTRIBUTED SUBSTANTIALLY UNI-PLANAR CONDUCTIVEPROJECTION MEANS SECURED TO THE BOTTOM SURFACE OF SAID BODY INCONDUCTIVE CONTACT THEREWITH, AND A LAYER OF ADHESIVE MATERIAL ON SAIDBOTTOM SURFACE AND BEING SUBSTANTIALLY FLUSH WITH SAID PROJECTION MEANSFOR SECURING THE SHIELD TO A METAL SURFACE WITH SAID PROJECTION MEANS INCONDUCTIVE ENGAGEMENT WITH THE METAL SURFACE.